How do you know if a woman is mad at you?

She will snub you .That very action indicate she is mad at you .

Says " Nothing, I am Fine" and other things, grumpy/angry face., swear, slamming things or that kinda stuff. People can tell when I'm angry well by my facial expressions lol 🙈

She will likely say.. "I'm FINE!"

You try talking to her and she throws whatever is closest to her at you 

You ask her what's wrong and in a nasty tone she replies, "Nothing."

You could try ASKING HER.

she might walk away or ignore you

she will say, nothing

If you suggested she calm down...

When you ask her what’s wrong and she says, “Nothing.”